# dumb blade tip speed question

Discussion in 'Lawn Mowing' started by milo, Jul 4, 2008.

1. ### GravelyNutLawnSite Bronze Memberfrom Wet part of FLMessages: 1,593

Actually they do get up to 60 RPS. Most small mower engines produce their rated HP at 3600 RPM.

2. ### Richard MartinLawnSite Fanaticfrom Greenville, NCMessages: 14,697

No, it's not. Tip speed is regulated by manufacturer insurance companies. Dixie Chopper mowers have been running tip speeds well in excess of 19,000 FPM for years on end.

3. ### Richard MartinLawnSite Fanaticfrom Greenville, NCMessages: 14,697

There's a little weird math going on here....

Why are you mutiplying the engine RPM by that pulley size? If the pulley is attached to the engine shaft then it's RPM will be the same as the engine's RPM.

4. ### Happy FrogLawnSite Bronze Memberfrom Navarre, FLMessages: 1,224

If one pulley is involved in then two pulleys are involved (at least). Your calculation can't be right...
Unless both pulleys are of the same size (then no pulley is involved)...

=

6. ### GenlandscapeLawnSite Memberfrom Spring Hill, FLMessages: 185

I think Phil has put this in perspective. Your avg. comm. mower blade speed is between 170 and 215 mph. 16-19,000fpm If you guys have the time to do the math you must need more lawns to mow= and yes 50 revs. per second IS possible. Indy car engines turn in excess of 16,000 rpm, and I have a buddy who races karts and has briggs engines that turn in excess of 10,000rpm. I want one for my eXmark but he doesnt reccomend it LOL!! Imagine the blade tip speed on that puppy!!

7. ### mtcjbLawnSite Memberfrom Munford, TNMessages: 37

that would scare the grass to the desired height lol

8. OP

### miloLawnSite Bronze Memberfrom fort myers flMessages: 1,357

indy cars turn more like 18000 to 19000 rpm's formula one cars turn up to like 24000rpm's and thats just sick lol

9. ### OldLawnMowerMan81LawnSite Memberfrom Milwaukie (Oak Grove), ORMessages: 66

Would it be more appropriate if I said what the spindle pulley diameter and RPM should be? It's the kind of information you don't see very often are what the spindle pulley speed and diameter should be.

10. ### ALC-GregHLawnSite Fanaticfrom PAMessages: 7,051

My friend in NY has a 19ft speed boat that idles at 24,000!!! It will spin in upwards of 56,000rpm. Talk about sick. He put a T63-A700 in the boat.